Perfect, thanks! --- In svg-developers@yahoogroups.com, Cameron McCormack <[EMAIL PROTECTED]> wrote: > > Hi Dan. > > dancooperstock: > > I'm working in Firefox 1.5. If I have the following SVG code: > > > > <line x1="10" y1="100" x2="10" y2="140" stroke="gray" stroke-width="1"/> > > <line x1="10" y1="100" x2="10" y2="170" stroke="gray" stroke-width="1"/> > > > > then the overlapping part (from y value 100 down to 140) looks darker > > than the non-overlapping part (from 140 down to 170). I've tried > > messing with opacity settings (like setting it to 1) but that makes no > > difference. > > The issue is with anti-aliasing and the way the coordinate system works > in SVG. If one user unit in your SVG maps to one pixel as rendered by > Firefox, and if anti-aliasing is used when drawing, then drawing > horizontal or vertical lines with integer coordinate values with a > stroke-width of 1 will result in the line straddling pixels. This is > because the integer coordinate values lie between the pixels in this > case, and a stroke-width of 1 will cause half of the stroke line to > drawn on one pixel, and the other half on the adjacent pixel--each with > 0.5 opacity. When the two coincident lines are drawn, their semi-opaque > pixels add together. > > You could do two things to avoid this: > > * force your lines to be rendered exactly on pixels by subtracting 0.5 > from your coordinates, e.g.: > > <g stroke="gray" stroke-width="1" transform="translate(-0.5)"> > <line x1="10" y1="100" x2="10" y2="140"/> > <line x1="10" y1="100" x2="10" y2="170"/> > </g> > > * set shape-rendering="crispEdges" to force anti-aliasing to be turned > off for these lines: > > <g stroke="gray" stroke-width="1" shape-rendering="crispEdges"> > <line x1="10" y1="100" x2="10" y2="140"/> > <line x1="10" y1="100" x2="10" y2="170"/> > </g> > > -- > Cameron McCormack ICQ: 26955922 > cam (at) mcc.id.au MSN: cam (at) mcc.id.au > http://mcc.id.au/ JBR: heycam (at) jabber.org >
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